The use of Fab-Fc recombinant antibodies for studying the mechanism of triggering the effector activities of immunoglobulins.

Immunoglobulin species, recombined from Fab and Fc fragments with anti-red cell specificity were used as cytophilic antibodies in studies of triggering the effector activity of immunoglobulins. Recombinant immunoglobulins containing a single Fab' appeared inactive in binding to cell receptors and triggering antibody dependent cellular cytotoxicity, while those with two Fab' exhibited an activity comparable to intact antibody IgG. The experiments indicate that Fab fragment may interact with Fc and inhibit its binding to cell receptors.